Electronic ink involves a display material that can be obtained by encapsulating charged particles of different colors with a micro-capsule technology or a micro-cup technology. Gray scales of display are obtained by applying a voltage to electrodes at two ends of electronic ink for a certain time to drive charged particles so as to control the amount of particles moving towards two ends of the electrodes. Electronic ink can be used to prepare electronic paper and the electronic paper can be used to further produce flat displays. Flat displays including electronic paper can function as a novel kind of information communication media with the display effect similar to common paper. Due to their features of erasability, light weight, thin thickness and low power dissipation, they are well suitable to be portable electronic readers to replace traditional books, and are also well suitable to be electronic tags, doorplates or information cards posted on merchandises, in front of guest room doors or wards in stores, hotels or hospitals.
Current flat displays including electronic paper typically include electronic paper tags, driving circuits, control modules and communication modules that are integrated together. In this kind of structure, each electronic paper tag is an independent display capable of receiving data through communication module and displaying data on the electronic paper tag. However such an electronic paper tag is not applicable for situations in which tag information is not required to be updated frequently such as doorplates, merchandise price labels due to overly high costs, because of the contained circuit modules.